We propose to develop a microfluidics device capable of detecting leukemic cells based on their cell- surface markers from patients with acute promyelocytic leukemia (APL). Approximately 7% of newly- diagnosed APL patients in the United States die within the first 48 hours, often of disseminated intravascular coagulation (DIC). In Latin America, where APL is the most frequent subtype of acute myeloid leukemia (AML), the mortality rate is significantly higher: 13% mortality within the first five days and an overall survival of about 50% [1]. This outcome is unfortunate, because it is preventable: if an APL diagnosis were made immediately when a patient first presents to a physician, then all-trans retinoic acid (ATRA) could be administered immediately. ATRA is life saving if given quickly to APL patients, because the incidence of DIC falls within hours of therapy. ATRA causes differentiation of APL cells and induces hematologic remissions initially on its own at a rate of >90%. Unfortunately, APL diagnosis requires expert hematopathologic review and careful immunophenotyping. When APL patients present late at night or on the weekends to their local doctor or emergency room (ER), they are often not diagnosed immediately, since hematologic consultation and clinical immunophenotyping are often unavailable then. Many hospitals do not even have the capability to make an acute leukemia diagnosis, due to insufficient hematopathologic expertise or lack of required equipment or trained technologists. Thus, many patients do not receive life-saving ATRA therapy right away. We propose to address this unfilled patient need with a point-of-care device capable of diagnosing APL, thereby allowing rapid initiation of appropriate therapy. Our device centers on-chip artificial pores that are functionalized with specific antibodies to screen, label- free, cells for size, shape, and specific cell-surface markers. The simple device allows true point-of-care, as it requires very little sample; virtually eliminates all sample preparation; has low-power requirements; and provides direct, accurate result in <5 minutes. Easily adaptable to a hand-held format, the results can display on a screen or be transmitted wirelessly to a physician's office (if performed at the patient's home) or hospital (if performed in a physician's office or local ER). Our device will perform complete blood counts and detect individual antigens important to immunophenotyping primary APL cells. The proposed two-year time line for device development is feasible given our current technology development and careful placement of milestones. Ultimately, our device could be adapted to many other clinical situations for rapid clinical monitoring. PI Lydia L. Sohn, Assoc. Prof. of Mechanical Eng. at the University of California, Berkeley will lead this NIH R21 project and fabricate/test the device. Co-PI Lucy A. Godley, M.D., Ph.D., and Assist. Prof. at The University of Chicago will provide interfacing among sample choice, experimental design, and clinical relevance. Senior Personnel, George Anwar, Ph.D. at UC Berkeley will lead in the software and hardware design and packaging of the device for point-of-care.